Upcycling of Poly(butylene adipate-co-terephthalate)into Dual Covalent Adaptable Networks through Chain Breaking-Crosslinking Strategy

Poly(butylene adipate-co-terephthalate)(PBAT),a widely studied biodegradable material,has not effectively addressed the problem of plastic waste.Taking into consideration the cost-effectiveness,upcycling PBAT should take precedence over direct composting degradation.The present work adopts a chain breaking-crosslinking strategy,upcycling PBAT into dual covalent adaptable networks(CANs).During the chainbreaking stage,the ammonolysis between PBAT and polyethyleneimine(PEI)established the primary crosslinked network.Subsequently,styrene maleic anhydride copolymer(SMA)reacted with the hydroxyl group,culminating in the formation of dual covalent adaptable networks.In contrast to PBAT,the PBAT-dual-CANs exhibited a notable Young's modulus of 239 MPa,alongside an inherent resistance to creep and solvents.Owing to catalysis from neighboring carboxyl group and excess hydroxyl groups,the PBAT-dual-CANs exhibited fast stress relaxation.Additionally,they could be recycled through extrusion and hot-press reprocessing,while retaining their biodegradability.This straightforward strategy offers a solution for dealing with plastic waste.

Enhanced Crystallization of Poly(butylene adipate-co-terephthalate)by a Self-assembly Nucleating Agent

Poly(butylene adipate-co-terephthalate)(PBAT)is a promising biodegradable flexible polymer but suffers from slow crystallization rate,making it less attractive for some applications like the injection-molded products in comparison with low-density polyethylene(LDPE).This work aimed to accelerate the crystallization of PBAT by adding a self-assembly nucleating agent octamethylenedicarboxylic dibenzoylhydrazide(OMBH).PBAT/OMBH composites with various OMBH contents(0 wt%,0.5 wt%,0.7 wt%,1 wt%,2 wt%,3 wt%and 5 wt%)were prepared through melt-mixing.The effect of OMBH on the crystallization behavior,morphologies and mechanical properties of PBAT was investigated.The highest nucleation efficiency value of 59.6%was achieved for PBAT with 0.7 wt%OMBH,much higher than that of 22.7%for PBAT with 0.7 wt%talc.Atomic force microscopy results showed that OMBH formed fine fibers and induced the formation of transcrystalline layers of PBAT.Fourier transform infrared spectroscopy(FTIR)combined with two-dimensional correlation spectra suggested that the intermolecular dipole-dipole N—H…O=C interactions but not hydrogen bond between OMBH and PBAT promoted the crystallization of PBAT in the initial period of crystallization.The presence of OMBH did not change the crystal form of PBAT but had positive contribution in enhancing its crystallinity and mechanical properties.This work is essential for preparing PBAT with high crystallization rate,enhancing its potential applications in injection-molded products.

Alkylpolyglycoside inducing poly (butylene terephthalate) non-woven graft copolymerization of chitosan

In order to improve the wettability and biocompatibility of the poly （butylene terephthalate） non-woven （PBTNW）, the method of surface modification is used to graft copolymerization of chitosan （CS） onto the PBTNW under alkylpolyglycoside （APG） inducing. The product is thoroughly characterized with the Fourier transform infrared spectroscopy （FrIR）, the electron spectroscopy for chemical analysis （ESCA）, the thermogravimetric （TG） and the scanning electron microscopy （SEM）. It is found that chitosan is successfully grafted onto PBTNW. In addition, the water contact angles, hemolysis tests and cytotoxicity evaluation tests show an improvement in wettability and biocompatihility as a result of graft copolymerization of chitosan. So the CS-grafted PBTNW exhibits greater superiority than the original PBTNW. The CS-grafted PBTNW can be a candidate for blood filter materials and other medical applications.

Enzymatic Degradation of Poly(butylenesuccinate)/Thermoplastic Starch Blend

The degradation of thermoplastic starch blend in the presence of commerciala-amylase and unpurified amylase of microbial origin was investigated.The blends consisting of thermoplastic starch and poly(butylene succinate)have potential use in packaging applications thus,it is essential to establish susceptibility to degradation.Molar mass loss,gravimetric weight loss,and molecular structure were evaluated.The changes in the surface were observed with scanning electron microscopy.It was confirmed that there was a significant difference in gravimetric weight loss between the blends degraded in two different solutions.Unpurified enzymes of microbial origin,produced by Rhizopus oryzae cultures decomposed analyzed materials more efficiently than purified commercial ones.Moreover,it was proved that in applied conditions,the molar mass of PBS fraction did not change significantly.

Improving Polylactide Toughness by Plasticizing with Low Molecular Weight Polylactide-Poly(Butylene Succinate)Copolymer

A low-molecular-weight polylactide-poly(butylene succinate)(PLA-PBS)copolymer was synthesized and incorporated into polylactide(PLA)as a novel toughening agent by solvent casting.The copolymer had the same chemical structure and function as PLA and it was used as a plasticizer to PLA.The copolymer was blended with PLA at a weight ratio from 2 to 10 wt%.Phase separation between PLA and PLA-PBS was not observed from their scanning electron microscopy(SEM)images and the crystal structure of PLA almost remained unchanged based on the X-ray diffraction(XRD)measurement.The melt flow index(MFI)of the blends was higher as the amount of PLA-PBS increased,indicating that the block copolymer did improve the mobility of the PLA chains.Moreover,tensile tests revealed that PLA with greater PLA-PBS copolymer exhibited higher elongation at break and it reached the maximum at 8 wt%of PLA-PBS in PLA,which was around 6 times higher than that of pure PLA.Furthermore,the glass transition temperature,measured by differential scanning calorimetry(DSC),markedly decreased with an increasing amount of the copolymer as it decreased from 61.2℃ for pure PLA to 41.3℃when it was blended with 10 wt%PLA-PBS copolymer.Therefore,the PLA-PBS copolymer was shown to be a promising plasticizer for fully biobased and toughened PLA.

DSC Study of Thermal Properties of Biodegradable Poly(Butylene Succinate-co-terephthalate)

Poly （ butylene succinate ） （ PBS ）, poly （ butylene terephthalate） （PBT） and poly （butylene succirmte-coterephthalate） （PBST）s were synthesized from dimethyl succinate and/or dimethyl terephthalate reacting with 1,4- butanediol through a process of transesterification/ polycondmsation in the presence of a high effective catalyst and characterized by means of GPC and DSC. The investigation was mainly focused on the influence of content of terephthalate units on the molecular weight and thermal properties of resulting polymers. It is revealed that the melting temperature and crystallinity of synthesized polymers decrease first with the increase of terephthalate units, then shift to rise gradually by DSC measurements. The results of Flory equation suggest sequence structure of PBSTs is random.

Nanocellulose: Effect on Thermal, Structural, Molecular Mobility and Rheological Characteristics of Poly(Butylenes Adipate-Co-Butylene Terephthalate) Nanocomposites

The concern with environmental preservation is a very current and relevant topic. Regarding polymers, the search for potentially ecofriendly matters has been the subject of scientific research. In this context, this work aimed to study the effect of adding nanocellulose (nCE) with 1, 3, and 5 wt.% on poly(butylene adipate-co-butylene terephthalate) (PBAT). Thermal, structural, relaxometric, and rheological assessments were carried out. Quantitative evaluation of PBAT copolymer by high field NMR revealed 56.4 and 43.6 m.% of the butylene adipate and butylene terephthalate segments, respectively. WAXD measurement on the deconvoluted diffraction patterns identified that nCE was a mixing of Cellulose I and Cellulose II polymorph structures. At any composition, nanocellulose interfered with the PBAT crystallisation process. Also, a series of new PBAT crystallographic planes appeared as a function of nanocellulose content. PBAT hydrogen molecular relaxation varied randomly with nanocellulose content and had a strong effect on the hydrogen relaxation. PBAT cold crystallisation and melting temperatures (Tcc and Tm) were almost unchangeable. Although Tcc did not change during polymer solidification from PBAT molten state, the sample’s degree of crystallinity varied with composition through the transcrystallization phenomenon. Nanocomposite thermal stability decreased possibly owing to the catalytic action of sulfonated amorphous cellulose chains. For the sample with 3 wt.% of nanocellulose, the highest values of complex viscosity and storage modulus were achieved.

TRANSESTERIFICATION OF POLY(BISPHENOL A CARBONATE) WITH AROMATIC AND ALIPHATIC SEGMENTS IN BUTYLENE TEREPHTHALATE-CAPROLACTONE COPOLYESTER

In this article, the transesterification of poly(bisphenol A carbonate) (PC) with butylene terephthalate-caprolactone copolyester at a weight ratio 50/50 (BCL(21)) was thoroughly investigated by proton nuclear magnetic resonance spectroscopy ('H-NMR), in conjunction with a model compound. The 1 H-NMR results of the annealed blend PC/BCL(21) show that the formation of bisphenol A-terephthalate ester units is the same as in the annealed blend of PC with PBT, and the transesterification actually occurs between PC and butylene terephthalate (BT) segments in BCL(21). By comparison with the model compound bisphenol A dibutyrate, the new signal appearing at δ= 2.56 in the 1H-NMR spectrum confirms the existence of bisphenol A caprolactone ester units resulting from the exchange reaction of PC with caprolactone (CL) segments. 1H-NMR analysis of the transesterification rates reveals that the reaction of PC with aromatic and aliphatic segments in BCL(21) proceeds in a random manner. The miscibility of the blend PC/BCL(21) copolyester is favorable for the transesterification of PC with BT segments and CL segments.

Thermal Behavior and Crystal Transition of Biodegradable Poly(butylenes adipate)Revealed by Two-Dimensional Correlation Spectroscopy

In the present study,thermal behavior and crystal transition of pure poly(butylene adipate)(PBA)upon heating process were investigated by FTIR spectroscopy.To gain further insight into the thermal behavior alteration and the phase transition of PBA,we performed two-dimensional(2D)correlation analysis.We found thatβ-form PBA crystal undergoes not only the melting process but also crystal transition upon the heating process.

Construction and evaluation of co-electrospun poly (butylene succinate)/gelatin materials as potential vascular grafts

In this study,a series of poly(butylene succinate)(PBSU)/gelatin composites were prepared by electrospinning.The morphology,physicochemical analysis,biomechanical properties,biocompatibility,and biodegradability of the materials were evaluated.The results showed that the ultimate tensile stress of the vascular PBSU/gelatin grafts at(95/5),(90/10),(85/15),and(80/20)was(4.17±0.54)MPa,(3.81±0.44)MPa,2.94±0.69 MPa and 2.11±0.72 MPa respectively,and the burst pressure was(282.7±22.3)kPa,(295.3±3.9)kPa,(306.8±13.9)kPa and(307.6±9.0)kPa respectively,which met the requirements of tissue-engineered blood vessels.Furthermore,the addition of gelatin improved the hydrophilicity and degradation properties of PBSU,thus enhancing cell adhesion and promoting the inward growth of vascular smooth muscle cells.In summary,the research in this paper provides a useful reference for the preparation and optimization of vascular scaffolds.

Influencing Factors and Process on <i>in Situ</i>Degradation of Poly(<i>Butylene Succinate</i>) Film by Strain <i>Bionectria ochroleuca</i>BFM-X1 in Soil

This is the first report on the PBS film degraded by any Bionectria ochroleuca fungal strain. The fungal strain BFM-X1 was isolated from an air environment on a vegetable field and was capable of degrading poly(butylene succinate) (PBS). The taxonomic identity of the strain BFM-X1 was confirmed to be Bionectria ochroleuca (showing a 99% similarity to B. ochroleuca in a BLAST search) through an ITS rRNA analysis. The bio-degradation of the PBS film by strain BFM-X1 was studied. Approximately 97.9% of the PBS film was degraded after strain BFM-X1 was inoculated at 28?C for 14 days. The degradation efficiency of BFM-X1 against PBS film under different soil environmental conditions was characterized. The results indicated that 62.78% of the PBS film loss was recorded in a 30-d experimental run in a sterile soil environment indoors. On adding strain BFM-X1 to a soil sample, the PBS degradation rate accelerated approximately fivefold. Furthermore, both temperature and humidity influenced the in situ degradation of the PBS by strain BFM-X1, and temperature may be the major regulating factor. The degradation was particularly effective in the warm season, with 90% of weight loss occurring in July and August. Scanning electron microscope observations showed surface changes to the film during the degradation process, which suggested that strain BFM-X1preferentially degraded an amorphous part of the film from the surface. These results suggested that the strain B. ochroleuca BFM-X1 was a new resource for degrading PBS film and has high potential in the bioremediation of PBS-plastic-contaminated soil

Crystallization and Dynamic Mechanical Behavior of Coir Fiber Reinforced Poly(Butylene Succinate)Biocomposites

The crystallization behavior,crystal morphology and form,and viscoelastic behavior of poly(butylene succinate)(PBS)and coir fiber/PBS composites(CPB)were investigated by differential scanning calorimetry(DSC),polarized optical microscopy(POM),X-ray diffraction(XRD)and dynamic mechanical analysis(DMA).The results of DSC measurement show that the crystallization temperature increases with the filling of coir fibers.POM images reveal that the spherulitic size and crystallization behavior of PBS are influenced by the coir fibers in the composites.XRD curves show that the crystal form of pure PBS and CPB are remaining almost identical.In addition,the storage modulus of CPB significantly increases comparing with the pure PBS.This predicted the dimensional stability and improved load-deformation temperature.In conclusion,the addition of coir fibers has a significant effect on the thermal properties of the matrix.

THERMAL PROPERTY, MISCIBILITY AND CRYSTALLIZATION BEHAVIOR OF POLY(3-HYDROXYBUTYRATE-co-3-YDROXYHEXANOATE) AND POLY(BUTYLENE SUCCINATE-ADIPATE) (PHBHHX/PBSA) BLENDS

Blends of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(butylene succinate-adipate) (PBSA), both biodegradable semicrystalline polyesters, were prepared with the ratio of PHBHHx/PBSA ranging from 80/20 to 20/80 by melt mixing method. Differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), dynamic mechanical thermal analysis (DMA), polarizing optical microscopy (POM) and wide angle X-ray diffractometer (WAXD) were used to study the miscibility and crystallization behavior of PHBHHx/PBSA blends. Experimental results indicate that PHBHHx is immiscible with PBSA as shown by the almost unchanged glass transition temperature and the biphasic melt.

Biodegradable Poly(butylene adipate-co-terephthalate)/Poly(glycolic acid) Films: Effect of Poly(glycolic acid) Crystal on Mechanical and Barrier Properties

Binary biodegradable polymers films, poly(butylene adipate-co-terephthalate)(PBAT) and poly(glycolic acid)(PGA), were prepared through batch melt mixing to obtain Film Ⅰ and Film Ⅱ under two different processing conditions. PGA crystals played a major role in enhancing the mechanical and barrier properties of the films. For Film Ⅰ, there were initial PGA crystals before the film blowing process, the PGA molecular chain further crystallized, forming the oriented crystallization of PGA. Moreover, the Xcand crystalline size in Film Ⅰ were higher than those in Film Ⅱ. Compared with the different processing methods, Film Ⅰ has excellent mechanical and oxygen barrier properties due to the crystallization and orientation. The tensile strength reached 45.0 MPa, and tear strength exceeded 138.2 kN/m, while the elongation at break was as high as 750% for PBAT/PGA 85/15 in Film Ⅰ. The WVTR, WVP coefficients, and OP coefficients of PBAT/PGA films were decreased obviously with increasing the PGA content both in Film Ⅰ and Film Ⅱ. Moreover, the barrier properties of oxygen in Film Ⅰ were better than that in Film Ⅱ. This work reveals a feasible processing technique by introducing of initial crystallization of PGA to blow PBAT/PGA films with excellent mechanical and barrier properties.

Recyclable thermally conductive poly(butylene adipate-co-terephthalate)composites prepared via forced infiltration

With the rapid development of electronic equipment and communication technology,the demand for polymer composites with high thermal conductivity and mechanical properties has increased significantly.However,its nondegradable polymer matrix will inevitably bring more and more serious environmental pollution.Therefore,it is urgent to develop biodegradable thermally conductive polymer composites.In this work,biodegradable poly(butylene adipate-coterephthalate)(PBAT)is used as the matrix material,and vacuum-assisted filtration technology is employed to prepare carbon nanotube(CNT)and cellulose nanocrystal(CNC)networks with high thermal conductivity.Then CNT-CNC/PBAT composites with high thermal conductivity and excellent mechanical properties are prepared by the ultrasonic-assisted forced infiltration method.Both experiment and simulation methods are used to systematically investigate the thermally conductive and dissipation performances of the CNT-CNC/PBAT composites.Above all,a simple alcoholysis reaction is applied to realize the separation of the PBAT matrix and functional fillers without destroying the conductive network skeleton,which makes it possible for the recycling of thermally conductive polymer composites.

Unlocking the Potential of Poly(butylene succinate)through Incorporation of Vitrimeric Network Based on Dynamic Imine Bonds

Poly(butylene succinate)(PBS)exhibits many advantages,such as renewability,biodegradability,and impressive thermal and mechanical properties,but is limited by the low melt viscosity and strength resulted from the linear structure.To address this,vitrimeric network was introduced to synthesize PBS vitrimers(PBSVs)based on dynamic imine bonds through melt polymerization of hydroxyl-terminated PBS with vanillin derived imine containing compound and hexamethylene diisocyanate using trimethylolpropane as a crosslinking monomer.PBSVs with different crosslinking degrees were synthesized through changing the content of the crosslinking monomer.The effect of crosslinking degree on the thermal,theological,mechanical properties,and stress relaxation behavior of the PBSVs was studied in detail.The results demonstrated that the melt viscosity,melt strength,and heat resistance were enhanced substantially without obvious depression in crystallizability,thermal stability,and mechanical properties through increasing crosslinking degree.In addition,the PBSVs exhibit thermal reprocessability with mechanical properties recovered by more than 90%even after processing for three times.Furthermore,PBSV with improved melt properties shows significantly improved foamability compared to commercial PBS.This research contributes to the advancement of polymer technology by successfully developing PBS vitrimers with improved properties,showcasing their potential applications in sustainable and biodegradable materials.

聚丁二酸丁二醇酯熔融缩聚增黏特性

为解决生物可降解聚丁二酸丁二醇酯(PBS)长期正常储存过程中易发生降解而导致分子量下降的难题,通过熔融缩聚增黏方法实现了PBS分子量的提升。研究了反应温度、反应时间、初始特性黏度以及熔体膜厚等对PBS特性黏度、分子量、热性能和流变性能的影响。结果表明:PBS分子量随熔融缩聚增黏温度升高而升高;220℃反应60min,PBS特性黏度即可从1.049dL/g升至2.072dL/g;PBS初始黏度越低其增黏速率越高;而PBS的熔体膜厚与其增黏反应速率呈反比;PBS特性黏度的升高导致结晶困难,进而使其熔点下降。流变测试结果表明随着特性黏度升高,PBS熔体强度与热稳定性均提升,能满足重新加工和使用的需求,通过熔融再聚合方法可有效解决PBS因降解而无法满足其后续加工和使用需求的难题。

Synthesis and Characterization of Poly（butylene adipate-co-terephthalate） Catalyzed by Rare Earth Stearates

Rare earth （Nd, Y, La, Dy） stearates have been synthesized and used as single component catalysts for the polycondensation of dimethyl terephthalate, adipic acid and 1,4-butanediol for the first time preparing biodegradable poly（butylene adipate-co-terephthalate） （PBAT） with high molecular weight, The microstructures of PBAT were characterized by ^1H NMR spectra. The PBAT exhibits good mechanical properties such as high tensile strength （ca. 20 MPa） and long break elongation （〉700%）.

Biodegradable Foaming Material of Poly(butylene adipate-co-terephthalate)(PBAT)/Poly(propylene carbonate)(PPC)

A biodegradable blend foaming material of poly(butylene adipate-co-terephthalate)(PBAT)/poly(propylene carbonate)(PPC)was successfully prepared by chemical foaming agent and screw extrusion method.First,PBAT was modified by bis(tert-butyl dioxy isopropyl)benzene(BIBP)for chain extension,and then the extended PBAT(E-PBAT)was foamed with PPC using a twin(single)screw extruder.By analyzing the properties of the blends,we found that Young’s modulus increased from 58.8 MPa of E-PBAT to 244.7 MPa of E-PBAT/PPC 50/50.The viscosity of the polymer has a critical influence on the formation of cells.Compared with neat PBAT(N-PBAT),the viscosity of E-PBAT increased by 3396 Pa·s and E-PBAT/PPC 50/50 increased by 8836 Pa·s.Meanwhile,the dynamic mechanical analysis(DMA)results showed that the storage modulus(E’)at room temperature increased from 538 MPa to 1650 MPa.The various phase morphologies(“sea-island”,“quasi-co-continuous”and“cocontinuous”)and crystallinity of the blends affected the spread velocity of gas and further affected the foaming morphology in E-PBAT/PPC foam.Therefore,through the analysis of phase morphology and foaming mechanism,we concluded that the E-PBAT/PPC 70/30 component has both excellent strength and the best foaming performance.

淀粉的改性及其对淀粉/PBAT/碳酸钙复合材料结构和性能的影响

采用甘油、六偏磷酸钠(SHMP)和聚乙二醇(PEG)改性木薯淀粉并制备改性淀粉/聚己二酸对苯二甲酸丁二醇酯(PBAT)/碳酸钙复合材料,采用傅里叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、差示扫描量热仪(DSC)、热失重分析仪(TG)等对改性淀粉和复合材料进行分析,研究改性淀粉对复合材料结构和性能的影响。结果表明,甘油的外增塑作用和PEG、SHMP的内增塑作用使淀粉化学结构改变、无定形成分增加,淀粉颗粒由饱满的圆球状变成了不规则的大颗粒,250℃前稳定性提高,250℃后稳定性降低,有利于使用加工和热分解,不同改性剂改性淀粉结晶熔融行为存在差异;复合不会改变PBAT、碳酸钙和淀粉的原有晶型,但相容性的差异导致复合材料热性能和力学性能的差异,改性淀粉增加了复合材料的韧性,甘油、SHMP和PEG的协同改性使淀粉与PBAT、碳酸钙的相容性最佳,复合材料的综合性能最好。